BACKGROUNDIncreased risk of bladder cancer has been reported in diabetic patients. This study was to investigate the roles of mitogen-activated protein kinase kinase (MEK) 1 and 2 in the regulation of human insulin- and insulin glargine-induced proliferation of human bladder cancer T24 cells.

METHODSIn the absence or presence of a selective inhibitor for MEK1 (PD98059) or a specific siRNA for MEK2 (siMEK2), with or without addition of insulin or glargine, T24 cell proliferation was evaluated by cell counting kit (CCK)-8 assay. Protein expression of MEK2, phosphorylation of ERK1/2 and Akt was analyzed by Western blotting.

RESULTST24 cell proliferation was promoted by PD98059 at 5 - 20 µmol/L, inhibited by siMEK2 at 25 - 100 nmol/L. PD98059 and siMEK2 remarkably reduced phosphorylated ERK1/2. Insulin- and glargine-induced T24 cell proliferation was enhanced by PD98059, suppressed while not blocked by siMEK2. Insulin- and glargine-induced ERK1/2 activation was blocked by PD98059 or siMEK2 treatment, whereas activation of Akt was not affected.

CONCLUSIONMEK1 inhibits while MEK2 contributes to normal and human insulin- and insulin glargine-induced human bladder cancer T24 cell proliferation.

Blotting, Western ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Flavonoids ; pharmacology ; Humans ; Insulin ; pharmacology ; Insulin Glargine ; Insulin, Long-Acting ; pharmacology ; MAP Kinase Kinase 1 ; antagonists & inhibitors ; metabolism ; MAP Kinase Kinase 2 ; genetics ; metabolism ; MAP Kinase Signaling System ; drug effects ; genetics ; Phosphorylation ; drug effects ; RNA, Small Interfering ; genetics ; physiology ; Urinary Bladder Neoplasms ; metabolism

In order to study the effect of insulin-like growth factor 1 (IGF-1) on proliferation of myeloma cell line KM3 and the role of MAPK pathway phosphorylation in this process, the cell cycle distribution shift of KM3 after incubation with series concentration of IGF-1 was detected by flow cytometry. Phosphorate-Erk1/2, the key molecule of MAPK pathway, was examined by Western blot after KM3 cells being pretreated with or without PD98059, the special inhibitor of Erk1 and Erk2 phosphorylation. The effect of specifically blocking Erk1 and Erk2 phosphorylation on proliferation and apoptosis of KM3 cells were detected with TUNEL staining. The results showed that the KM3 cells at S and G2/M phase increased and the phosphorylation of Erk1 and Erk2 became intensive when incubated with different concentration of IGF-1. PD98059 could decrease the phosphorylation of Erk1/2 induced by IGF-1 and induce the apoptosis of KM3 cells. It is concluded The phosphorylation of MAPK signaling pathway triggered by IGF-1 plays an important role in the proliferation of myeloma cell line KM3.
Cell Cycle ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Humans ; Insulin-Like Growth Factor I ; pharmacology ; MAP Kinase Signaling System ; physiology ; Mitogen-Activated Protein Kinase Kinases ; metabolism ; physiology ; Multiple Myeloma ; pathology ; Phosphorylation

To investigate the role of intracellular mitogen activated protein kinase (MAPKs, ERK, JNK and p38) signal pathways in IL-1beta -stimulated alpha-smooth muscle actin (alpha-SMA) expression in rat mesangial cells (rMC), alpha-SMA-promoter gene was transfected into rMC by electro-perforation method and the promoter activity was assayed after IL-1beta (10 ng/ml) stimulation. Protein expression of alpha-SMA was assayed by Western blot. The results were compared between the groups stimulated by IL-1beta with or without PD98059 and SB203580, which are thought to block ERK and p38 pathway, respectively. Dominant-negative-JNKK plasmid was co-transfected in rMC to block JNK pathway. The spatial distribution of alpha-SMA and microfilament-like structure was observed by a confocal laser scanning microscope or an electric microscope. After 6 or 24 h of incubation with IL-1beta, rMC underwent a phenotypic change, which was represented by up-regulation of alpha-SMA promoter activity and protein expression. An increase in alpha-SMA and microfilament-like structure was found around the cell nucleus. Block of JNK and/or p38 pathway greatly inhibited IL-1beta -induced alpha-SMA expression, and the block of p38 pathway also suppressed the basal level of alpha-SMA expression. In contrast, ERK pathway had no influence on the process. It is, therefore, concluded that IL-1beta -stimulated expression of alpha-SMA is due to its protein synthesis and cytoskeleton re-organization in activated rMC. Intracellular signal regulation of alpha-SMA expression seems to be mediated mainly by JNK/p38 pathways, but ERK appears to have no effect on the process.
Actins ; biosynthesis ; Animals ; Cells, Cultured ; Glomerular Mesangium ; metabolism ; Interleukin-1 ; pharmacology ; JNK Mitogen-Activated Protein Kinases ; MAP Kinase Kinase 4 ; MAP Kinase Signaling System ; drug effects ; physiology ; Male ; Mitogen-Activated Protein Kinase Kinases ; drug effects ; physiology ; Mitogen-Activated Protein Kinases ; drug effects ; physiology ; Muscle, Smooth ; metabolism ; Rats ; Rats, Sprague-Dawley

The object was to study the effect of ouabain on Jurkat cells and its possible mechanism. The effect of ouabain of low concentration on Jurkat cells was confirmed by MTT, while c-myc gene transcription was measured by RT-PCR, and the phosphorylation of MAPK (ERK1/2) as well as the expression of c-myc gene was tested by Western blot respectively. The results showed that ouabain at low concentration could induce the proliferation of Jurkat in a time-and dose-dependent manner. At the same time, the phosphorylation of MAPK (ERK1/2) and the expression of c-myc gene was enhanced. In conclusion, ouabain stimulates the intracellular MAPK signal pathway by acting on the Na, K-ATPase, and thus induce the proliferation of Jurkat cells, in which the regulation of c-myc gene expression may be involved.
Blotting, Western ; Cell Proliferation ; drug effects ; Dose-Response Relationship, Drug ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Humans ; Jurkat Cells ; MAP Kinase Kinase 1 ; metabolism ; MAP Kinase Signaling System ; physiology ; Ouabain ; pharmacology ; Phosphorylation ; drug effects ; Proto-Oncogene Proteins c-myc ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Time Factors

Hypoxia-induced 15-hydroxyeicosatetraenoic acid (15-HETE) is an essential mediator to constrict pulmonary arteries (PA). The signaling pathway involved in 15-HETE-induced PA vasoconstriction remains obscure. The aim of the present study was to test the hypothesis that hypoxic PA constriction induced by 15-HETE was possibly regulated by the extracellular signal-regulated kinase-1/2 (ERK1/2) pathway. PA ring tension measurement, Western blot and immunocytochemistry were used in the study to determine the possible role of ERK1/2 in 15-HETE-induced PA vasoconstriction. The organ bath for PA rings tension study was employed. Adult male Wistar rats were raised in hypoxic environment with fractional inspired oxygen (FIO2, 0.12) for 9 d. PA 1~1.5 mm in diameter were dissected and cut into 3 mm long rings for tension study. ERK1/2 up-stream kinase (MEK) inhibitor PD98059, which blocks the activation of ERK1/2, was used. The results showed that pretreatment of PD98059 significantly blunted 15-HETE-induced PA vasoconstrictions in the rings from hypoxic rat. Moreover, in endothelium-denuded rings, PD98059 also significantly attenuated 15-HETE-induced vasoconstriction. Phosphorylation of ERK1/2 in pulmonary arterial smooth muscle cells (PASMCs) of rat was enhanced evidently when stimulated by 15-HETE. Thus, the data suggest that ERK1/2 signaling pathway is involved in 15-HETE-induced hypoxic pulmonary vasoconstriction.
Animals ; Flavonoids ; pharmacology ; Hydroxyeicosatetraenoic Acids ; antagonists & inhibitors ; pharmacology ; Hypoxia ; physiopathology ; MAP Kinase Signaling System ; physiology ; Male ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; drug effects ; Pulmonary Artery ; cytology ; drug effects ; physiopathology ; Rats ; Rats, Wistar ; Vasoconstriction ; drug effects

BACKGROUNDThe survival ratio of implanted mesenchymal stem cells (MSCs) in the infarcted myocardium is low. Autophagy is a complex "self-eating" process and can be utilized for cell survival. We have found that atorvastatin (ATV) can effectively activate autophagy to enhance MSCs survival during hypoxia and serum deprivation (H/SD). The mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) pathway is a non-canonical autophagy pathway. We hypothesized that the MEK/ERK pathway mediated ATV-induced autophagy of MSCs under H/SD.

METHODSMSCs were pretreated with ATV (0.01-10 µmol/L) under H/SD for three hours. For inhibitor studies, the cells were pre-incubated with the MEK1/2 inhibitor U0126. Cell autophagy was assessed by acidic vesicular organelles (AVO)-positive cells using flow cytometry, autophagy related protein using Western blotting and autophagosome using transmission electron microscopy.

RESULTSAutophagy was elevated in the H/SD group compared with the normal group. ATV further enhanced the autophagic activity as well as the phosphorylation of ERK1/2 evidenced by more AVO-positive cells ((8.63 ± 0.63)% vs. (5.77 ± 0.44)%, P < 0.05), higher LC3-II/LC3-I ratio (4.36 ± 0.31 vs. 2.52 ± 0.18, P < 0.05) and more autophagosomes. And treatment with U0126 downregulated the phosphorylation of ERK1/2 and attenuated ATV-induced autophagy.

CONCLUSIONThe MEK/ERK pathway participates in ATV-induced autophagy in MSCs under H/SD, and modulation of the pathway could be a novel strategy to improve MSCs survival.

Animals ; Atorvastatin Calcium ; Autophagy ; drug effects ; Cell Hypoxia ; physiology ; Cells, Cultured ; Flow Cytometry ; Heptanoic Acids ; pharmacology ; MAP Kinase Signaling System ; drug effects ; Male ; Mesenchymal Stromal Cells ; cytology ; drug effects ; ultrastructure ; Microscopy, Electron, Transmission ; Pyrroles ; pharmacology ; Rats

OBJECTIVETo discuss the relationship between estradiol and the mitogenic activated protein kinase signal transduction pathway and the expression of the MAPK in the MCF-7 breast cancer cell-line.

METHODSEpithelial growth factor (EGF) and different concentration of estradiol to induce the expression of phosphospecific ERK1/2 (pERK1/2) in MCF-7 cell line was used and the expression of pERK1/2 with western-blotting was detected. Then antiestrogen ICI 182780 and MAPK inhibitor PD98059 to inhibit the expression of pERK1/2 was used. The cell cycle of MCF-7 was detected by FACS.

RESULTSEGF could significantly induce the expression of pERK1/2. Estradiol could also induce the expression of pERK1/2, but the intensity was less than the induction of EGF. The percentage of cells in the G(2)/M cell cycle after estradiol induction increased (18.38%) compared to the control group (10.52%) (P < 0.05).

CONCLUSIONSMAPK is an important regulatory signal in breast cancer. Its measurement in breast cancer tissues provides information about the degree of activation of various growth factor pathways. This molecule may also provide a molecular target for compounds designed to block cell proliferation.

Breast Neoplasms ; enzymology ; pathology ; physiopathology ; Cell Proliferation ; drug effects ; Estradiol ; pharmacology ; Female ; Humans ; MAP Kinase Signaling System ; drug effects ; physiology ; Mitogen-Activated Protein Kinases ; drug effects ; metabolism ; Receptors, Estrogen ; metabolism ; Signal Transduction ; Tumor Cells, Cultured

OBJECTIVETo investigate the role and significance of ATP-sensitive K+ channels in the pathological process of hypoxia hypercapnia-induced pulmonary vasoconstriction (HHPV) and the relationship with ERK1/2 signal pathway in rats.

METHODSWe made the third pulmonary artery rings of SD rats, used the model of pulmonary artery rings perfusion in vitro. Under acute hypoxia hypercapnia condition, and observed the effects of the three stages of HHPV incubated by glybenclamide(Gly) and the combined application of Gly and U0126. At the same time, the values of rings' tension changes were recorded via the method of hypoxia hypercapnia conditions reactivity.

RESULTSUnder the normoxia condition, the values of the third pulmonary artery rings tension were relatively stable, but under the hypoxia hypercapnia condition, we observed a biphasic pulmonary artery contractile response compared with N group (P < 0.05, P < 0.01). When the third pulmonary artery rings incubated by Gly, it's phase II persistent vasoconstriction was enhanced compared with the H group (P < 0.05, P < 0.01), and the phase I vasoconstriction was also heightened. Moreover, under the hypoxia hypercapnia condition, U0126 could significantly relieve the phase II persistent vasoconstriction compared with HD group (P < 0.05, P < 0.01) induced by Gly, but the phase I acute vasoconstriction and the phase I vasodilation had no changes (P > 0.05).

CONCLUSIONGly may mediate HHPV via activating ERK1/2 signal transduction pathway.

Animals ; Glyburide ; pharmacology ; Hypercapnia ; metabolism ; physiopathology ; Hypoxia ; metabolism ; physiopathology ; In Vitro Techniques ; MAP Kinase Signaling System ; physiology ; Male ; Pulmonary Artery ; drug effects ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Vasoconstriction ; drug effects

OBJECTIVETo investigate the role of extracellular signal-regulated kinase 1/2 on the inhibition of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) on the proliferation and collagen synthesis of cultured rat pulmonary fibroblasts induced by platelet-derived growth factor (PDGF).

METHODSPulmonary fibroblasts were prepared from lungs of neonatal Wistar rats as described previously. Cells were divided into 4 groups: (1) control group (0.4% FBS group); (2) PDGF (10 ng/ml) stimulated group; (3) PD98059+PDGF group (25 micromol/L PD98059+10 ng/ml PDGF); (4) AcSDKP+PDGF group (10(-8) mol/L AcSDKP+10 ng/ml PDGF). All experiments were performed in the fourth passages. Metabolic activity of fibroblasts was observed by MTT, and expressions of type I and type III collagen were measured by immunocytochemistry and western blot. Expressions of phospho-ERK1/2 and ERK1/2 were detected by western blot.

RESULTSCompared with control group, exposure of pulmonary fibroblasts to 10 ng/ml PDGF increased cell metabolic activity, expression of type I and type III collagen and phosphorylation of ERK1/2. 25 micromol/L PD98059 and AcSDKP both could inhibit the metabolic activity of pulmonary fibroblasts, type I and type III collagen synthesis and phosphorylation of ERK1/ 2 induced by PDGF, with significant differences (P < 0.05). AcSDKP+PDGF group compared with PDGF stimulated group, metabolic activity of pulmonary fibroblasts decreased to 77.4%. Immunocytochemistry result showed that in AcSDKP+PDGF group, expressions of type I and type III collagen decreased to 69.3% and 67.2% compared with those of PDGF stimulated group. Western blot result showed that in AcSDKP+PDGF group, expressions of type I and type III collagen decreased to 92.4% and 78.0%, phospho-ERK1/2 decreased to 83.5% compared with those of PDGF stimulated group, with significant differences (P < 0.05).

CONCLUSIONERK1/2 plays an important role in the inhibition of AcSDKP on the proliferation and collagen synthesis of cultured rat pulmonary fibroblasts induced by PDGF.

Animals ; Cell Proliferation ; drug effects ; Cells, Cultured ; Collagen ; biosynthesis ; Fibroblasts ; drug effects ; metabolism ; physiology ; MAP Kinase Signaling System ; physiology ; Oligopeptides ; pharmacology ; Platelet-Derived Growth Factor ; pharmacology ; Rats ; Rats, Wistar

OBJECTIVE: To investigate the effects of propofol combined with hypoxia on cognitive function of immature rats and the possible role of p38 pathway and tau protein in mediating such effects. METHODS: Ninety 7-day-old (P7) SD rats were randomized for daily intraperitoneal injection of propofol (50 mg/kg) or lipid emulsion (5.0 mL/kg) for 7 consecutive days. After each injection, the rats were placed in a warm box (38 ℃) with an oxygen concentration of 18% (hypoxia), 21% (normal air), or 50% (oxygen) until full recovery of the righting reflex. Another 90 P7 rats were similarly grouped and received intraperitoneal injections of p-p38 blocker (15 mg/kg) 30 min before the same treaments. The phosphorylated tau protein, total tau protein and p-p38 content in the hippocampus were detected using Western blotting. The spatial learning and memory abilities of the rats were evaluated with Morris water maze test. RESULTS: Compared with lipid emulsion, propofol injection resulted in significantly increased levels of p-p38, phosphorylated tau and total tau proteins in rats with subsequent hypoxic or normal air treatment ( < 0.05), but propofol with oxygen and injections of the blocker before propofol did not cause significant changes in the proteins. Without subsequent oxygenation, the rats receiving injections of propofol, with and without prior blocker injection, all showed significantly prolonged latency time and reduced platform-crossing times and third quadrant residence time compared with the corresponding lipid emulsion groups ( < 0.05). With oxygen treatment, the rats in propofoland blocker-treated groups showed no significant difference in the performance in Morris water maze test from the corresponding lipid emulsion group. The results of Morris water maze test differed significantly between blocker-propofol group and propofol groups irrespective of exposures to different oxygen levels ( < 0.05), but not between the lipid emulsion and blocker group pairs with exposures to different oxygen levels. CONCLUSIONS Propofol combined with hypoxia can affect the expression of tau protein through p38 pathway to impair the cognitive function of immature rats, in which oxygen plays a protective role.
Animals ; Cognitive Dysfunction ; etiology ; metabolism ; Hippocampus ; chemistry ; Hypnotics and Sedatives ; pharmacology ; Hypoxia, Brain ; complications ; metabolism ; MAP Kinase Signaling System ; Maze Learning ; drug effects ; physiology ; Memory ; drug effects ; physiology ; Propofol ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; tau Proteins ; analysis